Nonwoven fabrics are used in absorbent articles, such as sanitary products and disposable diapers, cleaning products, such as wipers, and medical goods, such as masks, and such products employ nonwoven fabrics with performance suitable for the purpose of the products and their intended location of use.
With absorbent articles, for example, it is necessary to employ nonwoven fabrics that expand and contract in response to bodily movement during wear or use, without creating an uncomfortable feeling for the user. Disposable diapers require nonwoven fabrics with high elasticity and strength sufficient to prevent tearing during extension, as well as satisfactory feel on the skin and air permeability.
PTL 1 discloses, as a nonwoven fabric with excellent air permeability, a three-dimensional sheet material comprising a material having a first layer and a second layer adjacent thereto, the first layer and second layer being partially bonded by joining sections in a prescribed pattern, the first layer forming a three-dimensional spatial shape between the joining sections, the second layer being composed of a material exhibiting elastomeric behavior, and the entire sheet also exhibiting elastomeric behavior as well as having air permeability. In the spatial sheet material described in PTL 1, the fibers composing the second layer are heat treated above the temperature at which heat shrinkage begins to cause shrinkage of the second layer, thereby creating a spatial structure.